Posted by Jen on .
A 10.8g sample of a gas has a volume of 5.25L at 25 degrees Celsius and 766mmHg.
If 2.3g of the same gas is added to this constant 5.25L volume and the temperature raised to 68 degrees Celsius, what is the new gas pressure?

Chemistry 
DrBob222,
Use PV = nRT and solve for n (from the first 10.8 g sample). Then
moles = n = grams/molar mass.
You know N and g, solve for molar mass.
Then convert 2.3 g to moles (moles = grams/molar mass), add to moles at the beginning, and use PV = nRT again to solve for P.